/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to you under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.calcite.adapter.enumerable;

import org.apache.calcite.plan.Convention;
import org.apache.calcite.plan.RelTraitSet;
import org.apache.calcite.rel.RelCollations;
import org.apache.calcite.rel.RelNode;
import org.apache.calcite.rel.convert.ConverterRule;
import org.apache.calcite.rel.core.Aggregate;
import org.apache.calcite.rel.logical.LogicalAggregate;
import org.apache.calcite.util.ImmutableIntList;


/**
 * Rule to convert a {@link LogicalAggregate}
 * to an {@link EnumerableSortedAggregate}.
 *
 * @see EnumerableRules#ENUMERABLE_SORTED_AGGREGATE_RULE
 */
class EnumerableSortedAggregateRule extends ConverterRule {
  /** Default configuration. */
  public static final Config DEFAULT_CONFIG = Config.INSTANCE
      .withConversion(LogicalAggregate.class, Convention.NONE,
          EnumerableConvention.INSTANCE, "EnumerableSortedAggregateRule")
      .withRuleFactory(EnumerableSortedAggregateRule::new);

  /** Called from the Config. */
  protected EnumerableSortedAggregateRule(Config config) {
    super(config);
  }

  public RelNode convert(RelNode rel) {
    final LogicalAggregate agg = (LogicalAggregate) rel;
    if (!Aggregate.isSimple(agg)) {
      return null;
    }
    final RelTraitSet inputTraits = rel.getCluster()
        .traitSet().replace(EnumerableConvention.INSTANCE)
        .replace(
            RelCollations.of(
                ImmutableIntList.copyOf(
            agg.getGroupSet().asList())));
    final RelTraitSet selfTraits = inputTraits.replace(
        RelCollations.of(
        ImmutableIntList.identity(agg.getGroupSet().cardinality())));
    return new EnumerableSortedAggregate(
        rel.getCluster(),
        selfTraits,
        convert(agg.getInput(), inputTraits),
        agg.getGroupSet(),
        agg.getGroupSets(),
        agg.getAggCallList());
  }
}
